The present invention relates to a method and apparatus for the exchange of data between a towing vehicle and one or more trailers. More specifically, the present invention relates to utility vehicles, where the towing vehicle and the trailer(s) are electrically connected to each other.
One prior art method is disclosed in U.S. Pat. No. 5,142,278 (Moallemi, et al, dated Aug. 25, 1992), which is incorporated herein by reference. This patent describes a towing vehicle electrically connected with two trailers via an electrical supply line. To transmit data between the towing vehicle and the trailers, the trailers transmit a modulated identification signal on the power line coupling the towing vehicle and the trailers. Data may consist e.g., of identification signals of the trailers, as well as temperature and pressure values in the trailers. This data is available in the towing vehicle, and is transmitted via a radio link to a central office. The central office can thereby control the location of the vehicles, as well as additional data exchanges. There is no radio link between the towing vehicle and the trailers.
Furthermore, EP 0 793 838 B1, equivalent to U.S. Pat. No. 5,831,519 (Lohmann, et al, dated Nov. 3, 1998), which is incorporated herein by reference, discloses a traffic control system for transportation systems. This control system provides one data processing unit in the towing unit, and another in the towed unit. The two data processing units can exchange information by wireless transmission. This type of prior art system is used primarily for theft protection.
Finally, EP A1 1 013 533 (Graeber, dated Jun. 28, 2000), which is incorporated herein by reference, discloses a process for the determination of the physical sequence of connected train vehicles, and an arrangement to carry out the process (train baptism). In this case, information is transmitted from radio systems built into the vehicles, when called for by a train master, via a radio-based data communication system connected to the train. To identify the vehicles common to a train, a coded identification signal is transmitted to the vehicles via the main air line, and the vehicle radio devices confirm the signal during determination of the sequence.
For a road utility vehicle, it is particularly desirable to exchange data and commands among the electronic braking systems (EBS) in the motor vehicle and in the trailers. This type of data communication has a positive effect upon the braking behavior and stability of the vehicle train.
While trailer and motor vehicle EBS are generally designed for stand-alone operation, cooperation between the two systems is desirable. As such, a vehicle movement dynamics (VMD) control contained in the EBS can exchange data between the trailer and the motor vehicle, and can e.g., brake individual wheels of the trailer whenever necessary.
For this type of data exchange, i.e., via an electrical line, a standardized interface is defined in ISO 11992. This interface enables the exchange of data via an electrical connection line, designated as CAN bus. As such, a matching identification for towing vehicle and corresponding trailer is not necessary. In practice, however, the above-mentioned interface is not in common use, and can not be assumed to be present. Moreover, an alternative connection line of the EBS itself by means of a data cable would not be a practicable method.
It can be assumed that future data transmissions between a towing vehicle and one or several trailers will be implemented via a radio connection. As such, the towing vehicle and the trailer(s) would each contain a two-way transmitting/receiving module for data exchange. A short range (less than 100 m) would be sufficient for such a radio connection. Further, the radio transmission must be confined to the towing vehicle and its connected trailers, so as not to interfere with any other trailers or towing vehicles located nearby.
It is therefore an object of the present invention to enable the reliable identification of a towing vehicle and its connected trailer(s) when communicating by radio transmission. As a result, a radio message will be recognized and carried out only by the appertaining, interconnected towing vehicle and trailer(s).
In accordance with an illustrative embodiment of the present invention, a method for the exchange of data between a towing vehicle and an attached trailer, which are connected electrically via a connection line and are equipped for transmitting and receiving radio signals, comprises the following steps:
a. upon starting up the towing vehicle, transmitting an identification signal from the towing vehicle,
b. the towing vehicle also simultaneously modifying the status of the connection line,
c. upon the trailer receiving the identification signal transmitted from the towing vehicle, and simultaneously recognizing the modified status of the connection circuit, the trailer then storing the identification signal, so that subsequent communication between the towing vehicle and the trailer is enabled by means of the identification signal.
The inventive design can also be used with multiple trailers attached to the towing vehicle, where all the trailers are similarly equipped.
In an alternative embodiment, the identification signal can be generated as a result of braking or directional signaling, in lieu of a start up signal.
In yet another embodiment, a predetermined number of simultaneous identification signals and connection circuit status changes are required for enabling communication between the towing vehicle and the trailer(s).